Carbon
dioxide released
by man near ground level is heavier than air and
sinks in air relatively quickly rather than rising up to the upper
atmosphere to become a so-called greenhouse gas in the upper atmosphere. While
sinking, it stratifies from air; after sinking and stratifying, it tends
to remain close to the ground. The carbon dioxide can then dissolve in soil
water or alternatively it may find its way down to low-lying water bodies or
down to ocean level where it can readily mix and dissolve in water or react
with water to form weak carbonic acid. Carbon dioxide is also removed
immediately from the lower atmosphere by rainfall.
Measurements of the
concentration of carbon dioxide in the atmosphere, as shown by the Keeling Curve, have been
performed continuously only since 1958 at Mauna Loa, Hawaii, unlike carbon
dioxide measurements before 1958, shown in red in the graph displayed here and in
non-green in this chart.
In the nineteenth and twentieth centuries A.D., many
measurements of the atmospheric concentration of carbon dioxide were higher
than present-day carbon dioxide measurements and there was no runaway
greenhouse-gas global warming effect.
Carbon dioxide is constantly
being added by jet aircraft to the atmosphere just above the tropopause, the
boundary region between the troposphere and the stratosphere. Jet aircraft fly
above the troposphere to avoid turbulence. The troposphere ranges in height
from 7 km at the poles to 16 km at the equator.
Hawaii is a major point destination for aircraft approaching and a major point source for aircraft leaving.
The Mauna Loa data is
obtained at an altitude of 3.4 km. Aircraft approaching and leaving Hawaii fly
at altitudes greater than 3.4 km. Carbon dioxide emitted by jet aircraft does not
sink straight down without any horizontal displacement due to winds and natural
diffusion.
State of
Hawaii Department of Transportation air traffic statistics for the calendar
years 1994 through 2005 show that Hilo International Airport alone had 108,462
takeoffs and landings in 2005 compared to 86,292 takeoffs and landings in 1994.
This is a 25% increase over ten years. Graphs of atmospheric carbon dioxide
concentrations measured at Mauna Loa Observatory also show an increase over
this same time period.
Replacing most present-day
air travel with earth surface travel would have a measurable effect on reducing
carbon dioxide concentrations in the atmosphere, but may do little to reduce
the overall greenhouse effect because natural water
vapour is by far the most significant greenhouse gas.
“The IPCC has always overstated the importance of
carbon dioxide as a greenhouse gas and under-estimated the importance of water
vapour”, according to Warwick Hughes here.
Email concerning this web page may be sent to David Wozney at dpwozney@ocii.com.
